


make this sin sincere

by krus



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Sex, Established Relationship, First Time, M/M, Modern Era, Plot What Plot/Porn Without Plot
Language: English
Status: Completed
Published: 2020-04-13
Updated: 2020-04-13
Packaged: 2021-03-01 22:01:41
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,586
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23634280
Author URL: https://archiveofourown.org/users/krus/pseuds/krus
Summary: Dimitri's never been good at being vocal about his needs, much less in something like this. “I was thinking, maybe… if you’d like it, that is, that we could…” He bites his lip.“Anything you want,” Sylvain tells him, moving to cup his cheek, running his thumb over it tenderly. “I want you to enjoy yourself.”It’s tender, just enough to bolster Dimitri’s confidence. Still, it takes him a few more moments to admit it: “I want you to… take me.”Their first time.
Relationships: Dimitri Alexandre Blaiddyd/Sylvain Jose Gautier
Comments: 11
Kudos: 117





	make this sin sincere

**Author's Note:**

> i imagined this as a veryyyyyyy vaguely defined modern/college AU, _not_ a pre-timeskip/academy-era fic! sorry for any confusion!

Given that he’s been dating Sylvain of all people for months now, it’s difficult to not think about it. Sylvain makes his experience very well known in the way he takes Dimitri apart every time they kiss, always keeping Dimitri wanting the slightest bit more. Sylvain knows what he’s doing, too, if that impish smirk on his face after he gets Dimitri flushed scarlet and breathing heavily is anything to go by.

They’re taking it slow, though. Sylvain told Dimitri once, late into the night when vulnerability comes so much easier, that he wanted this— _them_ —to be different from his flings. The memory invariably puts a smile on Dimitri’s face—it's a level of consideration that Dimitri is unaccustomed to.

That’s not to say that there’s no precedence for it. Throughout the past couple of weeks, there’s been a few times when they’ve ended up rutting against one another or using their hands. Sylvain makes the most beautiful noise when he comes—a soft, strangled whimper that Dimitri dreams about a little too often.

The breaking point is when Dimitri’s dreams go a little further than that. It’s all well and good to rehash past experience, even if it’s inconvenient to deal with the ramifications in the morning. There comes a morning, though, when Dimitri wakes up with the image of Sylvain taking him and whispering sweet nothings into his ear prominent in his mind. 

There’s no coming back from that. As much as Dimitri tries to push the thought out of his mind, it keeps coming back like clockwork, to the point where he can’t focus in his classes. The little they’ve done has been distracting enough, but the thought of giving himself over to Sylvain, of being so wholly connected, of the lovely tenderness with which Sylvain would take him… It’s tempting in a way that nothing else is.

The next time they kiss, Dimitri is impatient and insistent, clinging almost desperately to Sylvain. It doesn’t take long for Sylvain to comment “Eager, are we?” with a pleased little smirk on his face. Sylvain’s already straddling Dimitri, weighing down him pleasant and sure.

Sylvain’s lips are ever-so-slightly flushed red—not enough. Dimitri wants them scarlet and swollen. He hums noncommittally in response to Sylvain’s teasing, not quite sure how to put his desires into words. 

“It’s good, you know,” Sylvain murmurs as if he’s telling Dimitri a secret. “I like it.” As if in reward, he shifts his weight to one elbow, running his thumb over Dimitri’s bottom lip oh-so-slowly before shifting his weight back and leaning down to kiss Dimitri again.

Sylvain knows Dimitri well, knows that he loves the drag of Sylvain’s teeth on his bottom lip, the slide of their tongues against one another’s. Sylvain gives Dimitri everything he could want, including that sweet friction that Dimitri was so anxious to chase at first—now, Dimitri meets him, ruts right up against Sylvain as he grinds down. Sylvain always makes a sweet little noise at that, something that’s maybe even better than everything else Sylvain is doing to him.

But Sylvain knows Dimitri well, knows his limits, and pulls away soon enough to lather attention over his neck, kissing right where it’s sensitive and biting ever so gently, leaving the vaguest of marks. Dimitri’s nails dig into Sylvain’s back as he does so, little gasps leaving him as he seeks more friction.

Sylvain is hard and heavy against him, and all Dimitri can think of is how it might feel to go further this time. How badly he _wants_ to go further this time. “Sylvain,” he mutters cautiously, trying to choose his words properly.

Sylvain pauses, shifting his weight to look at Dimitri. “Yeah, babe? Do you need me to stop?”

A little too quickly—“That’s not it.” He averts his eyes. He’s never been good at being vocal about his needs, much less in something like this. “I was thinking, maybe… if you’d like it, that is, that we could…” He bites his lip.

“Anything you want,” Sylvain tells him, moving to cup his cheek, running his thumb over it tenderly. “I want you to enjoy yourself.”

It’s tender, just enough to bolster Dimitri’s confidence. Still, it takes him a few more moments to admit it: “I want you to… take me.”

Sylvain freezes. “You _what_?”

Anxiety pools in Dimitri’s stomach. “Only if you want to, of course—”

“Only if I _want_?” Sylvain laughs, a little tight. “Dimitri, I’ve thought about it so many times I’ve lost count.” Dimitri’s breath catches in his throat, heart skipping a beat. Has Sylvain thought about it just like Dimitri has, unable to focus during the day, pleasuring himself to the idea of it in the dead of night? “I’ll make you feel so good, sweetheart, just you wait—”

Dimitri swallows thickly, shifting against Sylvain. Moving his hand to tangle it in Dimitri’s hair, Sylvain kisses Dimitri again, but with a hunger Dimitri hasn’t experienced before. There’s intent in this kiss, a promise that sends shivers down his back. Sylvain tastes like him already; he must taste like Sylvain, too. He’s eager to find out every other way Sylvain will leave his mark.

Sylvain pulls away suddenly, frowning as he looks down at Dimitri. “You’ve gotta get this off,” he tells Dimitri as he tugs at Dimitri’s shirt. It comes off quickly, after that, as do the rest of their clothes—neither of them are in the mood to be coy about that. 

As Dimitri kicks his briefs to the floor, Sylvain asks, “You still good?” It’s the first time they’ve been fully naked in front of one another, and although Dimitri can’t shake the nervousness, the anticipation is far more intense. 

He nods, quick and sure. In response, Sylvain’s gaze darkens with a mix of pleasure and intent as he stares down at Dimitri, making Dimitri’s heart skip a beat. Sylvain’s never looked at him quite that way before. “You’re so pretty like this, you know? Lying beneath me, all worked up just for me—” Sylvain sighs sweetly. “I wanna suck you off while I finger you.”

Dimitri chokes out a moan at the thought. He’s thought about this before, too, and a strangled little _please_ escapes him before he can help it.

Sylvain grins, opening his bedside drawer and grabbing what must be some lube before readjusting his position. It’s a little awkward, the dorm bed just barely big enough to accommodate it, but Sylvain doesn’t seem to care. He takes Dimitri’s cock in his hand, brushing his finger across the tip, spreading around the precum there. Dimitri bites the inside of his cheek hard.

“You know I want to hear you,” Sylvain chides as he opens the vial. He spreads a generous amount over his fingers, running them around Dimitri’s entrance almost teasingly. The lube is colder than Dimitri expected, making him tense a little, to which Sylvain whispers, “I’ve got you, babe. Relax.” 

Sylvain starts placing kisses on Dimitri’s thighs, getting closer and closer to his cock with each one, but never quite to it. Sylvain glances up at Dimitri for a moment before whispering “I want you to remember this,” as he starts sucking hickeys into Dimitri’s thighs. Dimitri gasps as he does so—he’ll see those whenever he changes, evidence of how well Sylvain took him, a mark of belonging. It’s almost too much.

Sylvain’s finger slips in, then, a weird sensation. Dimitri can’t help but tense up at it, but that’s also when Sylvain finally, blessedly moves to take Dimitri’s cock in his mouth, licking gently at the head in a way that has Dimitri’s legs trembling. Sylvain holds one of his legs down as he takes Dimitri in deeper, enveloping Dimitri’s cock in a wet heat that his imagination holds no candle to. 

Sylvain’s mouth is heavenly. It takes all of Dimitri’s self-control to not jerk up into Sylvain’s mouth, especially as his tongue traces the underside of Dimitri’s cock, right on the sensitive vein. Dimitri tangles his hands in Sylvain’s hair, at which Sylvain hums, pleased, torturously sending vibrations all down Dimitri’s cock. Dimitri whimpers, tiny and high-pitched.

The only thing keeping him from spilling deep down Sylvain’s throat is Sylvain’s finger inside him, still uncertain and unfamiliar. Sylvain sees it fit then to add another finger, though, and begin scissoring him—that’s even more peculiar, but good in a way that Dimitri can’t quite place the longer it goes on. Then Sylvain hits _something_ inside of him that has Dimitri’s back arching, and he barely gets out a gasp before he comes. 

“I’m so sorry, I—I didn’t think… didn’t expect that so suddenly,” Dimitri mumbles, scratching at his cheek. “Are you—alright?”

Sylvain, instead of responding verbally, swallows, something that sears itself into Dimitri’s memory. He takes his free hand and rubs at the edge of his mouth, not that he needed to. Dimitri’s cock twitches at the sight despite itself. “You didn’t have to—”

“I wanted to, Dimitri,” Sylvain replies easily, taking his fingers out of Dimitri. “And stop apologizing. How hot it was to feel you come on my fingers makes up for it.”

Dimitri averts his eyes for lack of anything better to say, blushing at the forwardness. Even after all this time, he’s still not quite used to it. When he looks back to Sylvain, he notices that Sylvain is still hard, probably painfully so with the amount of precum dripping down his cock. “I—”

“Don’t you worry about it,” Sylvain tells him with a wink. “You’ve already done more than enough.”

“What if I want to keep going?” Dimitri asks defiantly. The way Sylvain’s fingers felt inside him for that one moment—if that was Sylvain’s cock instead, rubbing against it insistently, not to mention Sylvain’s weight holding him down… 

Sylvain’s eyes widen. “You want me to bring you off again?”

Dimitri nods, tiny and unsure.

“Goddess,” Sylvain mutters. “You’re going to be the death of me, you know that?” He moves to kiss Dimitri again, and Dimitri can taste himself on Sylvain’s tongue ever-so-faintly. It should be disgusting, and yet it somehow isn’t. Something about the evidence of the mark he’s left on Sylvain, maybe.

Dimitri is hard again soon enough, much to Sylvain’s pleasure. Sylvain resumes his work fingering Dimitri, pointedly avoiding that spot inside him except for the most feather-light of touches that leave Dimitri gasping and begging. Sylvain doesn’t even bother to hide how his smile grows wider each time Dimitri’s _please_ gets a little more desperate.

Sylvain seems content enough to continue teasing Dimitri all day, fingering him at a leisurely pace with only occasional attention to his cock. Eventually, voice threatening, Dimitri asks him, “Haven’t you—done that enough?”

“You’re ready?” Sylvain glances up at him, pausing. “You sure?”

“ _Yes_ ,” Dimitri whines. “Sylvain, please just—”

“I got it, I got it. Don’t you worry your pretty little head. I’ll take care of you.” Sylvain pulls out his fingers, grabbing the lube again and slathering a liberal amount over his cock, sighing gently as he does so. “I’ll make you feel so good, Dimitri.”

Dimitri whimpers in something like affirmation as Sylvain places Dimitri’s legs on his shoulders, lining himself up. “It’s gonna hurt at first, but it gets really good really quick, I promise. Tell me if you need to stop, okay?” Dimitri nods mindlessly, and that’s when Sylvain starts to push into him.

It’s the most peculiar feeling—full in a way Dimitri’s never felt before. It’s a little painful, for sure, but Sylvain goes slow enough that it’s almost a pleasant sting. Dimitri doesn’t realize he’s holding his breath, eyes closed tight, until Sylvain lets out a shaky exhale. Dimitri opens his eyes to see that Sylvain’s bottomed out, his fist clenched white against the bed, the other hand so tight around Dimitri’s thigh that it might bruise. Hopefully it will. 

“You— _ah_ , you feel so good.” It’s breathless, warping Sylvain’s voice in a way Dimitri’s never heard before. Dimitri’s cock twitches at the pure pleasure dripping from his voice. He’s the one making Sylvain feel that way, the only one who gets to see Sylvain this way anymore, and the knowledge sends heat rushing through Dimitri. “Goddess, I—just—let me know when you’re ready.”

It takes Dimitri a few minutes and a little bit of shifting that Sylvain gasps at so nicely to adjust. “I think—I think you can go ahead now.”

Sylvain pulls back a little, slow and gentle and sweet, before pushing back in. Each time he does it, the drag of his cock inside Dimitri becomes more and more tantalizing until Dimitri can barely stand the pace anymore. “Sylvain.” It comes out a little too desperately, but Dimitri hardly cares. “Please—faster.”

Sylvain does as Dimitri asks without a moment’s hesitation, as if he was barely holding back from doing that himself. The friction is unbearably gratifying, but what’s even more lovely is the way Sylvain looks as he fucks Dimitri—teeth dug deep into his bottom lip, eyes dark with pleasure, sweat collecting at his brow as he lets out breathy little moans. Dimitri reaches up for him, and Sylvain gets the message, leaning down so that they can kiss, open-mouthed and sloppy and disgusting. Dimitri’s beyond the point of caring.

The change in position also changes the angle that Sylvain’s cock is driving into Dimitri, and it glances against Dimitri’s prostate just right, just enough to make Dimitri gasp against Sylvain’s mouth. Sylvain smiles against his lips, adjusts himself a little, fucks Dimitri a little harder, making Dimitri tremble beneath him. 

“You’re so—beautiful like this,” Sylvain gasps as he moves to the side of Dimitri’s neck. He bites gently there before beginning to suck at the wound; there’s no way Dimitri will be able to hide the hickey it forms. “So beautiful, and all mine to take—”

“Yes,” Dimitri gasps, savoring the mark Sylvain is leaving on his neck. “Syl—Sylvain—I’m—please, Goddess—”

“I’ve got you,” Sylvain murmurs, grinding against Dimitri’s prostate. “You about to come, babe?”

Dimitri nods fervently. He feels Sylvain swallow against his neck, feels Sylvain’s hand fumble down between them to find Dimitri’s cock, stroking it clumsily but wonderfully all the same until Dimitri comes, making a mess of them. Sylvain inhales sharply as he does, thrusting into him one last time before coming deep inside him, a burst of warmth, with that whimper Dimitri loves so much.

The world is still for a moment or two, both of them catching their breath. Sylvain pulls out soon enough, and Dimitri looks up just in time to see Sylvain’s come start to run out of him. Dimitri does not miss the way Sylvain’s eyes fixate on the sight before tearing away.

Dimitri takes a deep breath and exhales. As he turns onto his side, he already feels an ache deep inside of him, pleasant right now even with the knowledge of the soreness it’ll bring later. They should change Sylvain’s sheets and clean up before anything else, but Dimitri is hardly in the mood to do anything but sleep, despite how disgusting it is. Sylvain must be in agreement, if the way he lies down next to Dimitri, slinging an arm over his shoulder and nuzzling into his neck, is any indicator.

“We can deal with the sheets later,” Sylvain tells him. “Let me just—hold you for now.”

Dimitri smiles to himself, silencing his objections.

**Author's Note:**

> sometimes you just gotta stay up half the night and write dimivain porn instead of sleeping
> 
> if you enjoyed, please leave comments or kudos! this is the first time i've written porn, and i'm super nervous about posting, so i'd especially appreciate it for this! thanks sm!


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